The magnetic presheath boundary condition with <b>E×B</b> drifts

Hutchinson, I. H.

doi:10.1063/1.871825

Cited by 41 publications

(26 citation statements)

References 3 publications

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“…Such a drift near the target modifies the Bohm condition. The simplest way to find how the Bohm condition is modified by the presence of the electric field was suggested by Hutchinson (1996). Consider the case where the magnetic field has both the parallel, B || , and perpendicular, B ⊥ , (with respect to the material surface) components, while the electric field, E, is parallel to the material surface, but E · B || = 0.…”

Section: Terminologymentioning

confidence: 99%

Physics of ultimate detachment of a tokamak divertor plasma

Krasheninnikov¹,

2017

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The basic physics of the processes playing the most important role in divertor plasma detachment is reviewed. The models used in the two-dimensional edge plasma transport codes that are widely used to address different issues of the edge plasma physics and to simulate the experimental data, as well as the numerical schemes and convergence issues, are described. The processes leading to ultimate divertor plasma detachment, the transition to and the stability of the detached regime, as well as the impact of the magnetic configuration and divertor geometry on detachment, are considered. A consistent, integral physical picture of ultimate detachment of a tokamak divertor plasma is developed.

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Section: Terminologymentioning

confidence: 99%

Physics of ultimate detachment of a tokamak divertor plasma

Krasheninnikov¹,

2017

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“…effort that has brought to light many important aspects of this physical system, such as the effect of collisions, 10-12 magnetic field angle, 9,12-14 E Â B and diamagnetic drifts, [15][16][17][18][19][20] and finite ion temperature. 9,21 Most of these studies provide a boundary condition for the parallel ion velocity at the MP entrance, whereas the boundary conditions for the other fluid quantities remain unclear.…”

Section: Introductionmentioning

confidence: 99%

Boundary conditions for plasma fluid models at the magnetic presheath entrance

et al. 2012

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The proper boundary conditions at the magnetic presheath entrance for plasma fluid turbulence models based on the drift approximation are derived, focusing on a weakly collisional plasma sheath with Ti≪Te and a magnetic field oblique to a totally absorbing wall. First, the location of the magnetic presheath entrance is rigorously derived. Then boundary conditions at the magnetic presheath entrance are analytically deduced for v||i, v||e, n, ϕ, Te, and for the vorticity ω=∇⊥2ϕ. The effects of E × B and diamagnetic drifts on the boundary conditions are also investigated. Kinetic simulations are performed that confirm the analytical results. Finally, the new set of boundary conditions is implemented in a three-dimensional global fluid code for the simulation of plasma turbulence and, as an example, the results of a tokamak scrape-off layer simulation are discussed. The framework presented can be generalized to obtain boundary conditions at the magnetic presheath entrance in more complex scenarios.

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“…Consequently if there is a self-consistent combination of density and velocity fields {n, M , M ⊥ = M ⊥0 } that satisfies the advection equations (10, 11) (and the drift equation, 4), any perpendicular vector field, M ⊥1 , that satisfies M ⊥1 .∇n = 0, also satisfies M ⊥1 .∇M = 0. We can therefore subtract any such M ⊥1 from M ⊥ without affecting the characteristic equations (10,11). In other words, the combination {n, M , M ⊥ = (M ⊥0 − M ⊥1 )} also satisfies the characteristic equations (though not the drift equation, 4).…”

Section: Accounting For Self-consistent Driftsmentioning

confidence: 99%

“…We choose axes such that B is aligned along x and M ⊥ = M hŷ along y. The requirements expressed by the characteristics (10,11) are that both…”

Section: Uniform Perpendicular-velocity Ansatzmentioning

confidence: 99%

“…The approximate one-dimensional diffusive treatment has been generalized [10] to include an additional perpendicular plasma drift velocity, accounting for the boundary-condition modification [11] that the transverse drift causes. Measuring the dependence of the ion collection current-density on orientation of oblique probe faces then allows one to deduce the perpendicular as well as the parallel external drift velocity.…”

Section: Introductionmentioning

confidence: 99%

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Oblique ion collection in the drift approximation: How magnetized Mach probes really work

Hutchinson

2008

Physics of Plasmas

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The anisotropic fluid equations governing a frictionless obliquely-flowing plasma around an essentially arbitrarily shaped three-dimensional ion-absorbing object in a strong magnetic field are solved analytically in the quasi-neutral drift-approximation, neglecting parallel temperature gradients. The effects of transverse displacements traversing the magnetic presheath are also quantified. It is shown that the parallel collection flux density dependence upon external Mach-number is n ∞ c s exp[−1 − (M ∞ − M ⊥ cot θ)] where θ is the angle (in the plane of field and drift velocity) of the object-surface to the magnetic-field and M ∞ is the external parallel flow. The perpendicular drift, M ⊥ , appearing here consists of the external E ∧ B drift plus a weighted sum of the ion and electron diamagnetic drifts that depends upon the total angle of the surface to the magnetic field. It is that somewhat counter-intuitive combination that an oblique (transverse) Mach probe experiment measures.

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The magnetic presheath boundary condition with E×B drifts

Cited by 41 publications

References 3 publications

Physics of ultimate detachment of a tokamak divertor plasma

Physics of ultimate detachment of a tokamak divertor plasma

Boundary conditions for plasma fluid models at the magnetic presheath entrance

Oblique ion collection in the drift approximation: How magnetized Mach probes really work

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